Strip end welding machine



May l2, 1970 J. D. MORLEY ETAL 3,511,961

STRIP END WELDING MACHINE 9 sheds-sheet 1 Filed May 31, .1966

May 12, 1970 J. D. MoRLEY E'rAL 3,511,951

snm END WELDING MACHINE A Filed May si. 196e 9 sheets-smet 2 gl f May 12, 1976 Y J. D. MORLEY ETAL l 3,511,961

STRIP 'END WELDING MACHINE Filed May 5.1, 1966 9 Sheets-Sheet 3 MPA/fw May 12, 1970 J. D. MORLEY ETAL 3,511,961

STRIP END WELDING MACHINE Filed May 51, 1966 n EN NNN

May 12,'19'70 I J. UMORLEY ETAL 3,511,951

STRIP END WELDING MACHINE Filed may 51, 196e y 9 sheetsheet s May 12, 1970 '.J. D. MORLY ETAL. 3,511,961

STRIP END WELDING MACHINE Filed mayl 51 196e 9 Sheets-Sheet 6 1X v lol* 213A May12, 1910 1D. MQ'RLEY E TL 3,511,961

STRIP END-WELDING MACHINE 9 'sheets-sheet v Filed May 3l, 1966 w www1 .NNN

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May l2, 1970 Filed May 51, 1966 J. DMoR| E:Y ETAL STRIP END WELDING MACHINE y 9 Sheets-lheet 8 May l2, 1970 J. D. MoRLEY ETAL 3,511,961

STRIP END WELDING MACHINE Filed May 51, 966 9 Sheets-Sheet 9 United States Patent O 3,511,961 STRIP END WELDING MACHINE John D. Morley, Bay City, and William F. Salbenblatt, Saginaw, Mich., assignors to Newcor, Inc., Bay City, Mich., a corporation of Delaware Filed May 31, 1966, Ser. No. 553,971 Int. Cl. B23k 9/12, 11/06 U.S. Cl. 219-83 7 Claims ABSTRACT F THE DISCLOSURE This invention relates to a welding machine and more particularly relates to an improved machine for rapidly welding together the ends of succeeding, nite length strips to produce a continuous elongated strip.

There is substantial need for strip end welding machines capable of satisfactory use with high speed, continuous processing devices of various kinds for steel strip material. Such machines are intended to add to the end of a steel strip being processed a further strip as the initial strip is being moved continuously through the processing device. More particularly, such machines are intended to form, in effect, an unbroken strip input to the processing device by sequentially adding new rolls of strip material, as required to the strip passing through the processing device. Normally, the tail end of the strip going into the processing device is stopped so that the head end of a new strip can be welded thereto, a suitable amount of slack being provided Vbetween the tail end and portion of the strip moving in the processing device to allow such stoppage of the tail. However, the relatively high strip speeds, for example, several thousand feet per minute, used in modern processing devices of various kinds require that welding the head of the new strip of material to the tail of the strip being processed be done very quickly since only a limited amount of slack can be provided between the welding zone and the processing device and hence, only a very limited amount of time is available for welding.

Known machines of this general type are normally provided with clamps for holding together the ends of the strips to be welded, a device for trimming the ends to be welded and means for welding the ends of the strips in an overlapped position. However, prior strip end welding machines of this general type have not been completely satisfactory on a number of counts.

For example, the strip end clamps used in prior machines to position the strip ends for trimming and welding have in general been unsatisfactory. The strip ends are desirably overlapped only by a relatively small amount in order to minimize the extra thickness of the finished sheet at the weld seam. Particularly high clamping forces are required during welding to prevent the strip ends from shifting from their overlapped condition in response to pressures and side forces exerted thereon by welding electrodes. Difficulty has arisen from this need for high clamping forces. Reaction-type devices, including pressure uid cylinders, screw jacks ICC or the like, have not been fully satisfactory for developing the clamping force, since the reaction force imposed upon the frame of the machine thereby during clamping is very high. As a result, therefore, machines using reaction-type clamping devices must either have excessively heavy frames to back up the clamping device or suffer deformation as the result of clamping.

Eelectromagnetic clamps avoid the above-mentioned problem but introduce further diculties. More specifically, placement of an electromagnetic clamp near the welding position changes the induction thereat and will cause losses, primarily eddy current losses. If on the other hand, the clamp is placed far enough from the welding zone to avoid such losses, it is then possible for the pressure of the welding electrodes to push the stripends apart and causel 'buckling of the strip ends.

In machines of this general type, it is common practice to clamp and trim the head and tail edges of the strips to be joined and then to move the clamps toward each other to bring the trimmed edges into overlapping relationship for welding. Slack must be provided in the incoming strip to allow movement of the entry clamp toward the weld position, the incoming strip normally being of substantial length and being wound on a large roll which has considerable rotation inertia. Inasmuch as the clamp moving mechanism is not normally constructed to overcome such inertia, extra mechanism has in the past been provided the needed slack in the entering strip. For example, in one known machine a lifting device is pivotally mounted below the strip. Upon actuation, the device rotates upwardly against the bottom of the strip and raises the adjacent portion thereof above its normal plane of travel to form a hump therein, thus producing the required slack. This arrangement is however, disadvantageous in that it requires an extra mechanism which adds cost, complexity and maintenance problems.

It is customary in machines of this general type to provide clamps which equal or exceed the width of the strips to be joined so that the strips can be clamped across their entire width in a positive manner. In reciprocating the clamps between spaced positions for welding and shearing, it is highly desirable that both sides of the clamp and hence of the clamped portion of the strip be moved identically to avoid any cocking or twisting of the clamped strip portion due to cocking of the clamp. The simple provision of a pair of axially aligned pressure fluid cylinders on opposite sides of the clamp carriage is generally unsatisfactory due to the difficulty of synchronizing the movements of the pressure fluid cylinder pistons precisely enough to prevent cocking of th'e clamps as they are reciprocated.

It is normally desired that the strips to be welded be coplanar during welding except for the overlapped end portions thereof so that after planishing of the welded seam the nished workpiece will be planar.

Early strip end welding machines were in general designed to weld the ends of relatively narrow strips. More recently, however, it has become desirable to provide machines capable of joining relatively wide strips. Furthermore, it is, as just mentioned above, desirable to overlap the strip ends to be 'welded by only a minimum amount. The amount of overlap in fact may be of the same order as the strip thickness. It has been found, in overlap welding wide strips, that the degree of overlap diminishes in front of the welding electrodes as they move across the lapped strip ends. It has been found, for example, that an initial .050 inch overlap of a pair of .050 inch thick strip endsmay diminish on a six foot wide strip by about .020 inch at the end of the seam, i.e., the overlap may diminish by as much as 40% of the initial overlap through 3 the length of the seam. Such change in overlap is regarded as too large and would tend to result in poorly welded sections in the joint since weld current density (which controls unit area weld heat) increases as overlap decreases. Moreover, the characteristics of the joint will be changed, and the joint may ha've, together with reduced strength, reduced thickness in the zone of reduced overlap.

In the past there has been some diiculty when the same machine is used to weld thin strips together and, alternatively, to weld together thicker strips. The diiculty arises from the fact that less overlap can be tolerated with relatively thin strips than with thicker ones while retaining reliable completion of joints of satisfactory strength. At the same time, it is generally desirable that overlap be no greater than necessary for satisfactory seam strength since additional overlap material adds to the thickness of the joint to an undesirable extent. Thus, if the normal overlap used on thick strips is provided for thin strips, the completed weld seam will be too thick. On the other hand, if the overlap normally used for thin strips is used for thick strips, the probability of an unsatisfactory weld rises sharply due to insufficient overlap.

Accordingly, the objects of this invention include provision of a welding machine for welding together the overlapped ends of successive strips passed therethrough and particularly adapted for welding strip ends of substantial width.

A further object is to provide a welding machine, as aforesaid, which is of simplified and improved construction, which can be produced at cost at least competitive with known machines of the same general type, which will be capable of reliable operation over a long operating life and which will require little or no maintenance, such maintenance being readily accomplished by persons generally acquainted with devices of this general type.

A further object of this invention is to provide a welding machine, as aforesaid, having an improved clamp for clamping the strips in a fixed position during welding thereof.

A further object of this invention is to provide a clamp, as aforesaid, fwhich is held closed by means of a magnetically generated force, in which the magnetic material and any windings of the clamp are spaced substantially from the welding zone, in which the clamp does not materially affect the inductance at the welding position, in which losses including eddy current losses at the 'welding position resulting from effects of the clamp are substantially eliminated.

A further object of this invention is to provide a clamp, as aforesaid, which positively prevents buckling of the strip between the clamped portion thereof and the welding position but lwhich does not tightly grip the strip between the clamped portion thereof and the welding position.

A further object of this invention is to provide a clamp, as aforesaid, which is capable of supplying the high clamping force required to hold a strip for narrow overlap welding but which imposes no corresponding reaction force on the rwelding machine and thus allows for relatively light machine construction.

A further object of this invention is to provide a welding machine, as aforesaid, in which a clamp is provided on the entry side of the machine (i.e., the side of a machine receiving the head end of a new strip), in which means are provided for moving the clamp along the axis of the incoming strip and in 'which the clamp moving means is capable of advancing the incoming strip to a position for welding after the end of the strip has been trimmed.

A further object of this invention is to provide a welding machine as aforesaid, including an improved mecha nism which is arranged for reciprocating the clamps toward and away from the lwelding position, which maintains the same rate of motion on both sides of the clamp and of the strip with high precision, which maintains the length of travel at the opposite ends of the clamp equal with high' precision, which' pre-vents cocking of the clamp with respect to the direction of its travel, |which prevents unintended cocking of the strip end during movement thereof by the clamp and which precisely locates the clamp transversely of its direction of travel.

A further object of this invention is to provide a clamp reciprocating device, as aforesaid, which is operable from one side of the strip" by a single motive source such as a pressure fluid'cylinder, which requires little room on the machine axially of .the strip, in which requires relatively little room in direction to lright angles of the plane of the incoming strip, in 'which the clamp reciprocating means includes synchronized, positive means for displacing each end of the clamp and in which the clamps can be made to reciprocate between limiting positions along the strip very rapidly.

A further object of this invention is to provide a welding machine, as aforesaid, including means for positively controlling the extent to which the strips to be joined are overlapped and in which the means controlling the extent of overlap are associated with the clamp reciprocating device.

A further object of this invention is to provide a welding machine, as aforesaid, including pivoting means supporting at least one clamp which is capable of cooking at least one of the strips slightly with respect .to its normal path for shearing and then returning the strip to a normally aligned position to increase the overlap at the termi nal end of the seam to be welded or is alternatively actuable to allow the strips to be trimmed with square ends'and to relatively cock said strips in a manner to increase the overlap at the terminal end of seam to be welded so as to compensate for the tendency of the strip ends to lose overlap during welding.

Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.

In-the drawings:

FIG. 1 is a partially broken side elevational view of a welding machine embodying the invention taken from theentry side thereof.

FIG. 2 is a partially broken top view of the machine of FIG. 1.

FIG. 3 is an enlarged, partially broken sectional view taken on the line III-III of FIG. 2.

FIG. 3A is a fragmentary section taken on the line IIIA-IIIA of FIG. 3.

FIG. 4 is an enlarged fragment of FIG. 3.

FIG. 5 is a partially broken end view of the apparatus of FIG. 3 taken from the rightward or exit end thereof.

FIG. 6 is a sectional view substantially as taken on the line VAI-VI of FIG. 5.

FIG. 6A is an enlarged fragmentary sectional view taken on the line VIA-VIA of FIG. 6.

FIG. 7 is a sectional View substantially as taken on the line VII-VII of FIG. 3.

FIG. 7A is a fragmentary section taken on the line VIIALVIIA of FIG. 7.

FIG. 8 is a partially broken, enlarged sectional view taken on the line VIII-VIII of FIG. 2.

FIG. 9 is a reduced, partially broken sectional view substantially as taken on the line IX-IX of FIG. 8.

FIG. 10 is a section taken on the line X-X of FIG. 9. FIG. 11 is an enlarged sectional view taken on the line XI-XI of FIG. 101.

FIG. 12 is a sectional view substantially taken on the line XII-XII of FIG. ll.

FIG. 13 is a sectional view taken on the line XIII-XIII of FIG. 12.

FIG. 14 is an enlarged fragment'of FIG. 3 showing the head and tail strip ends positioned for welding.

FIG. l5 is a schematic diagram showing the operation of the entry cla-mp in locating the head end of the entry strip for shearing.

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words upwardly, downwardly, rightwardly and leftwardly will designate directions in the drawings to which reference is made. The words forwardly and rearwardly will refer to the net direction of strip flow through the machine, forwardly being the normal flow direction, such flow being from left to right as indicated -by the arrow A in FIG. 3. The terms operator side and drive side will refer to the rightward and leftward sides, respectively, of the machine as indicated in FIG. l. The words inwardly and outwardly will refer to directions toward and away from respectively, the geometric center of the machine and designated parts thereof. Further, the terms tail end or just tail will refer to the end of the outgoing strip, that is, the strip on the exit side of the machine. The term head end or simply head will refer to the approaching end of .the incoming strip, that is, the strip on the entry side of the machine. The terms entry and exit will be applied to portions of the machine which a forwardly travelling strip will meet rst and last, respectively.

GENERAL DESCRIPTION In general, the objects and purposes of this invention are met by providing a strip end welding machine comprising a base upon which is slideably mounted a horizontally reciprocating, annular frame. The strips whose ends are to be welded pass axially through the frame transversely of its direction of reciprocation. The frame carries a shear for trimming the ends of the strips to be welded and welding and planishing rolls energizable for joining the overlapped strip ends. The machine includes base-mounted clamps on either side of vthe frame for gripping the strip ends to be joined.

Each clamp includes a pair of pressure members, preferably an electromagnet and a bed of magnetic material disposed on opposite sides of the strip end to be clamped. The electromagnet is energizable for attracting the bed for tightly gripping the strip end therebetween. The pressure members are spaced from the welding zone and each carries a nose of nonmagnetic material which extends toward the welding zone` and are spaced apart when said clamp is actuated to grip the strip end by a distance somewhat greater than the thickness of the strip end. The noses prevent buckling of the strip end between the welding zone and the pressure members. Means are provided for separating the pressure members of each clamp.

Each clamp is carried upon a carriage reciprocable along the axis of the adjacent strip tomove the clamped strip toward and away from the welding zone. The carriage is slideably supported on guide means fixed upon a platform above the base. A cross slide is carried by the platform beneath the carriage for reciprocation transversely of the axis of the strip. Angle blocks having parallel edge contact surfaces disposed at an acute angle to the path of the cross slide are carried thereby and slide with respect to wedge-shaped members lfixed to the underside of the carriage. Thus, reciprocation of the cross slide transversely of the strip elfects a corresponding reciprocation of the carriage through the angle block and wedges in a direction parallel to the strip axis. Suitable table means support the platforms with respect to the base so as to locate one of the clamps on the entry side of the frame and one on the exit side thereof.

In operation, the open entrance clamp is moved to its position closest to the welding zone. The head end is fed therethrough and preferably somewhat past the path of the welding rollers. The clamp then grips the head end and is retracted to a position remote from the welding zone to establish slack in theincoming strip. The head end is then trimmed. Thereafter, the entry clamp is returned to its position adjacent the welding zione to present the trimmed head end for welding. Means are provided to limit the extent of transverse movementof the entrance cross slide and thereby establish the limits of the entrance clamp and are adjustable to allow a greater overlap of thicker strips and a lesser overlap of thinner strips.

The platform on the entrance side of the machine is pivotally mounted on an axis spaced from the welding zone. Lift means are provided for pivoting the inner end of the platform upwardly on such axis to lift therewith the entrance clamp and to raise the head end of the entering strip above the tail end of the exiting strip so as to provide an overlap. The exit platform is pivotally secured to the table by a vertical bolt at one inner corner thereof and is loosely secured to the table at the remaining corners to prevent the platform from lifting off the table. Energizable means are provided for pivoting the platform to adjust the angle between the axes of the incoming and outgoing strips from an aligned position to a cocked position so that the overlap between the strip ends will increase in the direction of welding.

DETAILED DESCRIPTION (a) Basic structure The welding machine 10 embodying the invention and illustrated in FIGS. 1-3, is intended for welding the head end of an incoming strip I (FIG. 3) to the tail end of an outgoing strip O aligned therewith. The machine 10 has a base 11 which extends perpendicularly to the strips I and O and is substantially centered therebeneath.

In the particular embodiment shown, the base 11 is supported on the bottom of a pit 16 in the floor 17 of the machine site by leveling shims 18. The base 11 includes relatively short forward and rearward extensions 21 and 22 substantially centered on opposite sides of the base 11. The .base 11 is provided with a relatively deep channel 23 which opens upwardly and extends longitudinally thereof. Horizontally opposed, parallel ways 26 and 27 extend along the top of the base 11 and overhang the upper edges of the channel 23.

A vertically arranged, generally O-shaped frame 28 (FIGS. 1 and 3) has an elongated, horizontal lower portion 29 partially disposed in the channel 23. A plurality of longitudinally spaced mounting blocks are tixed to opposite sides of the lower portion 29 as indicated at 31 and 32 (FIG. 3) opposite the ways 26 and 27, respectively. Vertical guide rollers 36 and horizontal guide rollers 37 are supported by each of the mounting blocks 31 and 32 and bear against the upper, lower and opposed faces of the ways 26 and 27 to constrain the O-frame 28 to movement longitudinally of the ways 26 and 27. The lower portion 29 (FIG. 1) extends above the base 11 and is surmounted by generally U-shaped, downwardly opening upper portion 38. The O-frame 28 thus has longitudinally extending opening 30 therethrough defined between the upper and lower portions 28 and 29 thereof through which the incoming strip I may pass.

The O-frame 28 is reciprocable along the ways 216 and 27 'between a leftward limiting position shown in solid lines in FIG. l and a rightward limiting position shown in broken lines at 28A in FIG. l. The O-frame 28 is here reciprocated by an elongated screw 41 disposed in the rightward end of the channel 23 and rotatably driven by a suitable motor schematically indicated at 42. A exible cable holder carries control and power cables and hoses to the O-frame 28 from the base 11.

The O-frame 28 supports a shear 46 (FIG. l) adjacent the rightward end thereof which has vertically opposed upper and lower blades 47 and 48 extended longitudinally of the O-frame 28. The length of the blades 47 and 48 corresponds to the width of the widest strip to be welded by the machine 10 which in the particular embodiment shown is about inches. The blades 47 and 48 are supported for relative vertical movement for trimming the ends of the strips I and O. In the particular embodiment shown, for example, the lower blade 48 is secured to the top of a lower platen 51 vertically slideable on tracks 49 and S0 in the O-frame 28. Center folding links 52 and 53 each are pivotally fixed to the platen 51 and lower frame portion 29. The piston rod of a pressure fluid cylinder 54 connects through a drive bar 55 to the folding centers of the links 52 and 53 for unfolding and folding said links alternatively to move the blade 48 upwardly and downwardly, respectively.

The upper blade 47 is pendently supported from an upper platen 56 the ends of which are slideably mounted on tracks 57 and 58 for vertical sliding motion with respect to the O-frame 28. A pressure uid cylinder S9 is mounted longitudinally of the O-frame 28- adjacent the rightward end thereof and above the upper platen 56. The piston rod of the cylinder 59 is reciprocable for pivoting longitudinally spaced bell cranks 61 and 62. Links 63l and 64 suspend the ends of the upper platen 56 from the bell cranks 61 and 62. Cranks 61 and 62 are made to operate in unison for parallel motion by a tie bar 60. Thus, actuation of the cylinder 59 moves the upper blade 47 upwardly and downwardly. Alternatively, it is contemplated that the cylinder may be eliminated and replaced by further cylinders, not shown, mounted on the O-frame 28 for pushing directly downwardly on the upper plate 47, the bell crank 61 and 62 and links 63 and 64 being retained for maintaining the blade 47 horizontal during its vertical movement. Coordinated actuation of the cylinders 54 and 59 will bring the blades 47 and 48 forceably together to trim the end of a strip disposed therebetween. In the embodiment of FIG. 4, the upper blade is essentially of rectangular cross section and the lower blade is generally U-shaped in section to provide two spaced shear planes, the ends of the incoming and outgoing strips being trimmed along the plane nearest thereto. If desired, a failsafe latch 66 (FIG. l) may be provided for safety'purposes during maintenance to hold the upper platen 1n its uppermost position.

Vertically aligned welding roller electrodes 71 and 72 (FIG. l) are disposed between the shear 46 and the leftward end of the frame 28 and move rightwardly with the frame 28 to engage and roll along the upper and lower sides, respectively, of the seam to be welded. In the particular embodiment shown, the upper welding roll 71 is supported upon a vertically reciprocable fork 73 energized by a pressure fluid cylinder 74 mounted atop the frame 28. The lower roller 72 is vertically adjustably mounted on a lower fork 76, the vertical position of which is controlled by a hand wheel 77. Bus bars 78 and 79 for supplying welding current to to the rolls 71 and 72, respectively, extend from the forks 73 and 76 leftwardly along the upper and lower walls, respectively, of the opening 30 to the output terminals of a suitable current source, for example, a single phase welding transformer, a D.C. output -motor generator or a transformer-rectifier unit, such as that shown in application Ser. No. 420,949, filed Dec. 24, 1964, now Pat. No. 3,361,951 and assigned to the same assignee as the present application, mounted upon the leftward end of the frame 28. Suitable insulation indicated at 82 and 83 is provided to isolate the bus bars 78 and 79 and the electrodes 71 and 72 from the frame 28.

Vertically aligned planishing rollers 86 and 87 are disposed between the shear 46 and welding rolls 71 and 72 for tightly gripping the welded seam therebetween for reducing the thickness thereof and smoothing same as the frame 28 moves along the seam. In the particular embodiment shown, the upper planishing roller 86 is rotatably supported upon a post 88 vertically slidably disposed with respect to the frame 28 for reciprocation by tandem pressure uid cylinders 91 and 92. The lower planishing roller 87 is similarly supported upon a downwardly extending post 93 mounted upon the frame for verti-cal adjustment upon suitable rotation of an adjustment screw 94. In the particular embodiment shown, the central plane S (FIG. 3) of the shear is somewhat rearwardly offset from the common central plane W of the welding and planishing rollers.

The base extensions 22 and 21 (FIG. 3) carry upstanding entry and exit supports 96 and 97, respectively. The supports 96 and 97 carry entry and exit clamps 101 and 102, respectively, which extend into the O-frame opening 30 for gripping the head and tail ends, respectively, of the incoming and outgoing strips I and O, respectively.

Entry equipment generally indicated at 98 (FIG. 2) and exit equipment generally indicated at 99 extends away from the entry and exit supports 96 and 97, respectively, and among other functions, controls the transverse positioning of the strips I and O relative to each other and to the machine 10 described in detail in copendng application Ser. No. 553,970, filed May 3l, 1966. In addition, the entry equipment 98 supports a control panel 100 by means of which an operator can control the machine 10.

(b) Cocking mechanism Turning first to the exit support 97 (FIGS. 3-7A), same includes a table 111 (FIG. 3) fixed on the base extension 21 adjacent the way 27. The table extends transversely beneath the outgoing strip O preferably somewhat beyond the edges thereof. The table 111 has a top 112 upon which are disposed a plurality, here three, of wellspaced slide bars 113 (FIGS. 5 and 6) which parallel the direction A of strip travel through the machine 10'. A generally rectangular platform 116 is provided with slide bars 117 on the bottom wall 118 thereof. The slide bars 117 are located above the aforementioned slide bars 113 and rest thereupon to support the platform 116 upon and for horizontal sliding motion with respect to the table 111. The platform 116 is supported on the table 111 for pivotal movement with respect thereto such pivotal movement being controlled by a cocking mechaism 120 described immediately below. More particularly, the ends of the walls 112 and 118 extend beyond the remainder of the table 111 and platform 116 to form overlapping closely spaced anges.

Vertical holes 21 (FIGS. 6, 6a and 7) are provided through the bottom wall 118, preferably at each corner thereof. Corresponding holes 122, vertically aligned with the holes 121, appear at each corner of the top 112. One of the holes through the bottom wall 118 is of reduced diameter and is indicated at 123. The reduced diameter opening 123 is preferably one of those adjacent the frame 28 and more particularly is the upper, righthand hole of FIG. 6. Shoulder bolts pass downwardly through the openings 121 and 123 in the botto-m wall 118, the enlarged diameter upper portion 126 thereof being loosely received within the openings 121 and snugly but rotatably received within the opening 123. Suitable washers 127 loosely surround the enlarged diameter portion 126 of the bolts 124 above and below the wall 118. The reduced diameter portion 128 of each shoulder bolt 124 is snugly received within the aligned one of the openings 122 in the wall 112 and extend therethrough, suitable washers 129 snugly surrounding the reduced diameter portion 128 above and below the wall 112. The washers 129 and wall 112 are tightly gripped between the shoulder 131 of the shoulder bolt 124 and a nut 1,32 threaded on the lower end thereof. The wall 118 is snugly gripped between the head of the nut 124 and the uppermost one of the lwashers 129 but such grip is loose enough to allow sideways `movement of the bottom wall 118 with respect to the bolt 124 to the extent allowed by clearance be- -tween the enlarged portion 126 and the wall of the hole 121. The shoulder bolt disposed in the reduced diameter hole 123 will hereinafter be designated as pivot bolt since the platform is pivotable thereabout.

The Cocking mechanism 120 further includes a pressure fluid cylinder 134 (FIGS. 3, 5, 6 and 7) preferably located diagonally opposite the reduced diameter hole 123 in the bottom wall 118 of the platform 116. The pressure fluid cylinder 134 is pivotally supported at 136 upon a bracket 137 lwhich extends forwardly from the forward face of the table 111 and is rigidly affixed thereto. The pressure fluid cylinder 134 extends substantially in alignment with the outgoing strip O toward the O- frame 28 along the end of the exit support 97. The piston rod 138 of the cylinder 134 has an extension 139 affixed thereto. A lever arm 142 is fixed to the bottom wall 118 of the platform 116 and extends leftwardly (FIGSl. 3A and 6) therefrom above the table 111. The outer end of the lever arm 142 is pivotally affixed to the free end of the extension 139. Thus, reciprocation of the piston rod 138 of the cylinder 134 moves the lever arm 142 forwardly and rearwardly to pivot the platform 116 about the pivot bolt 125.

The leftward end (FIG. 6) of the bottom wall 118 of the platform 116 is notched as indicated at 143 between the shoulder bolts 124. Upstanding bosses 146 and 147 (FIGS. 3 and 6) are disposed on opposite sides of the lever arm 142 and are spaced therefrom. The bosses 146 and 147 are fixed to the upper face of the top wall 112 of the table 111 and extend upwardly therefrom into the notch 143. Preferably coaxial adjustment screws 148 and 149 extend through the bosses 146 and 1147, respectively, to adjustably limit the swing of the lever arm 142 therebetween and, hence to determine the orientation of the platform 116 at the ends of its swing. If desired, suitable abutment blocks may be provided on the arm 142 for contact with the screws 148 and 149, one of such abutment bocks being indicated at 151.

(c) Clamp reciprocating mechanism The exit support further includes a carriage 156 which is supported atop the platform 116 by suitable guide means generally indicated at 157 (FIGS. 3, 3A, 5 and 7) for reciprocation toward and away from the O-frame 28 in response to energization of reciprocation means generally indicated at 158.

In the particular embodiment shown, the guide means comprises a parallel pair of guide rods 161 and 162 aligned with the path of the strips I and O. The guide rods 161 and 162 are supported above the platform 116 by upstanding brackets one of which is indicated at 164. The brackets 164 are disposed adjacent the corners of the top of the platform 116 and are fixed to the ends of the guide conduits 161 and 162. The carriage 15'6 includes a plurality of bulkheads 166 which extend longitudinally thereof and to which are affixed cylindrical shells 167 coaxially telescoped over each of the guide rods 161 and 1-62. Suitable axial bearings 168 (FIGS. 3 and 4), here axial ball bearings, are provided within the shells 167 for engaging the periphery of the rods 161 and 162 whereby to support the carriage 156- for reciprocation along the guide rods 161 and 162 toward and away from the path of the welding electrodes.

The reciprocating means 158 comprises an elongated cross slide 171 (FIGS. 3, 3A, 5, 7 and 7A) which is snugly disposed for reciprocation in an upwardly opening slideway 172 recessed in the top of the platform 116. The slideway 172 extends longitudinally of the platform 116 from one end thereof to the other and is preferably substantially centered below the guide rods 161 and 162. Cover members 176, 177 and 178 (FIG. 7) are spaced along the length of the slideway 172 and are fixed to the platform 116 for retaining the cross slide 171 within the slideway 172. The cover members 176 and 178 are preferably disposed adjacent the ends of the slideway 172 and the cover member 177 is centrally disposed thereof. A pressure fluid cylinder 179l (FIGS. 3A, 5 and 7) is disposed at one end, here the leftward end, of the cross slide 171 in coaxial alignment therewith. The pressure fiuid cylinder 179 is supported by a bracket 181 fixed to the adjacent end of the platform 116. The cylinder 179 has a piston rod 182 which is fixed to the leftward end of the cross slide 171 whereby reciprocation of the piston rod 182 of the pressure fluid cylinder 179 will result in a corresponding reciprocation of the cross slide 171 along the slideway 172.

.Preferably identical, parallelogram-shaped angle blocks 186 and 187 are spaced between the cover members 176, 177 and 177, 178, respectively. The angle blocks 186 and 187 are affixed to the cros slide 171 by any convenient means, here including keys 188 aligned longitudinally of the cross slide, for reciprocation therewith. The angle blocks .each have contact surfacss 191 and 192 on opposite sides thereof which are parallel to each other and disposed at a small acute angle to the axis of the cross slide 171, such angle being slightly less than 30 degrees in the present embodiment. The contact surfaces 191 and 192 of the angle block 186 fit snugly between and slideably engage corresponding parallel contact surfaces 19'6 and 197 of a surrounding pair of wedge blocks 198 and 199 spaced respectively rearwardly and forwardly therefrom. Further wedge blocks 201 and 202, preferably identical to the blocks 198 and 199, are similarly snugly but slideably disposed against the contact surfaces of the angle block 187. The wedge blocks 198, 199, 201 and 202 are fixed by any convenient means such as screws, not shown, to the underside of the carriage 156. As a result, longitudinal movement of the cross slide 171 and therewith the angle blocks will displace the wedge blocks with the carriage 156 toward or away from the welding zone.

(d) Clamp mechanism Turning now to the details of the exit clamp 102 (FIGS. 3, 4 and 5) supported on the carriage 156, same comprises a bedplate 206 of magnetic material disposed at the inner edge of the carriage 156. The bedplate 206 preferably extends through the length of the carriage 156.

The bedplate 206 is recessed in a downwardly stepped portion 206 of the top of the carriage 156 so that the upper surface thereof is flush with the upper surface of the carriage 156. An electromagnet 207 (FIG. 4) covers the bedplate 206 and is energizable for magnetically attracting same with a high force density over the surface thereof. In the particular embodiment shown, the electromagnet comprises a generally M-shaped core 209 having longitudinally arranged downwardly facing grooves 211 and 212 in each of which is disposed a plurality of electrical conductors 213 defining a coil through which current from any convenient source, not shown, may be passed to energize the electromagnet for attracting same to the bedplate.

The strip O when disposed between the energized electromagnet 207 and bedplate 20'6 is firmly gripped therebetween and thus held `fixed with respect to the carriage 156. The clamp 102 has been found satisfactory for strips of either magnetic or nonmagnetic material. Moreover, the electromagnet has a sufficiently strong field that even relatively thick strip material may be clamped without serious loss of clamping force. In the particular embodiment shown, strip material .080 inch or more thick has been satisfactorily held by the clamp 102.

The inner edge of the electromagnet 207 is flush with the inner edge of the bedplate 206 and with the inner face of the carriage 156 with the clamp 102 in its innermost position nearest the weld zone, the electromagnet and bedplate are substantially spaced therefrom. Thus, the clamp 102 is at all times sufficiently spaced from the welding zone as to prevent changes in the inductancein the welding circuit due to the effect of themagnetic field of the clamp and hence to prevent any losses that might be generated by such field.

Preferably identical vertically opposed noses 216 and 217 are fixed to an extend the length of the inner walls of the magnet 207 and plate 206, respectively. The noses 216 and 217 are here of substantially L-shaped cross section having oppositely extending vertical fianges 218 and 219, respectively, which are affixed to the rear wall of the magnet 207 and to the rear walls of the bedplate 206 and carriage 156, respectively, by any convenient means such as screws not shown. The noses 216 and 217 have rearwardly extending, spaced horizontal flanges 221 and 222, respectively. The horizontal flanges 221 and 222 here include replaceable planar liners 23 and 24, respectively, delining the opposed faces thereof. The opposed faces of the noses 216 and 217, which in the particular embodiment shown are the opposed faces of the liners 223 and 224, are each slightly set back from the opposed faces of the magnet 207 and bedplate 206. As a result, a strip O tightly gripped between the magnet and bedplate will readily clear the noses. The inner ends of the liners 223 and 224 closely approach the path of weld rollers and preferably clear same by only a relatively small amount. Thus, the end of a strip O gripped in the clamp 102 will be prevented from buckling and thereby from shifting forwardly away from its desired position for welding by the close presence of the opposed surfaces of the noses 216 and 217 despite the relatively large distance between the welding zone and the magnet 207.

Pressure fluid cylinders 226 and 227 (FIGS. 5, 6 and 7) are vertically aligned and disposed at the opposite ends of the carriage 156 beneath the longitudinal axis of the magnet 207. Substantially rectangular brackets 228 and 229 (FIGS. and 7) are xed to the ends of the carriage 156 beneath the magnet 207 and pendently support the cylinders 226 and 227, respectively, rigidly on the carriage. The cylinders 226 and 227 have upwardly extending piston rods 231 and 232, respectively. Extension rods 233 and 234 are fixed to the upper ends of the push rods 231 and 232, respectively, and extend coaxially upwardly therefrom. The extension rods 233 and 234 are guided by bearings one of which is shown at 236 (FIG. 5) atlixed to the brackets 228 and 229, respectively, for axial sliding motion. -Ears 237 and 238 extend longitudinally from the ends of the magnet core 208 and are pivotally engaged by the upper ends of the extension rods 233 and 234. Thus, extension of the piston rods of the cylinders 226 and 27 raises the extension rods 233 and 234 and therewith the magnet core 208 when the latter is de-energized.

' In its raised position, the core 208 is substantially spaced above the bedplate 2,06 as indicated in broken lines at 239 in FIG. 3.

(e) Vertical offset mechanism Turning now to the entry support 96 (FIGS. 3 and 8- 13), same includes an upstanding pair of walls 242 and 243 (FIGS. 3, 8 and 9) spaced longitudinally of and xed supported upon the entry base extension 22. The walls 242 and 243 extend horizontally from the outer edge of the base extension 22 `to a point adjacent the way 26. Coaxial pivot bearings 246 and 247 are supported on the top surfaces 244 of the Walls 242 and 243, respectively, adjacent the outer ends thereof.

The entry support 96 further includes a platform 248 which is disposed above the walls 242 and 243 and extends longitudinally therebeyond. The platform 248 includes an upper top surface 249 as Well as a plurality of vertical, transversely extending -bulkheads one of which is indicated at 251 disposed beneath said top surface. Each of the pivot bearings 246 and 247 is loosely disposed between a pair of such bulkheads 251. The bearings 246 and 247 rotatably support pivot shafts 252 and 253, respectively, which extend between and are rigidly aflixed to the surrounding bulkheads 251 on the outer side of the platform 248 whereby the platform 248 is pivotally supported upon'the bearings 246 and 247. Vertically aligned abutment blocks 256 and 257 are disposed on the underside of the platform 248 and upper surface 244 of the walls 2.42 and 243, respectively, adjacent the O-frame 28 for supporting the inner side of the platform 248.

, Upstanding pressure lluid cylinders 258 and 259 are pivotally supported at the bottom vends thereof as indicated at 261 upon upstanding lugs 262 on the upper surfaceof the entry base extension 22. In the particular embodiment of the invention shown, the cylinders 258 and 259 are disposed adjacent to and between the walls 242 and 243. The cylinders 258 and 259 are spaced inwardly from the pivot bearings 246 and 247 toward the O-frame 28 and lie adjacent the inner ends of the walls 242 and 243. Said cylinders 258 and 259 have piston rods 263 and 264, respectively, extending upwardly between the bulkheads 248 terminated by clevices 266 and 267, respectively, at the upper ends thereof. The clevices 266 and 267 pivotally engage depending lugs, one of which is indicated at 268, which are fixed to the underside of the platform top.

Thus, extension of the pressure fluid cylinders 258 and 259 raises the inner side of the platform 2418, the platform pivoting on the pivot bearings 246 and 247. Thus, the portion of the entry support 96 located above the platform 248 is pivoted to raise the entry clamp 201 frorn. its normal lowerrnost position shown in the drawings. Thus, the head end of the incoming strip I can be raised above the tail end of the outgoing strip O to allow the strips to be overlapped and to avoid an endwise abutting thereof. Inasmuch as the head end of the incoming strip I need only be raised by an amount slightly in excess of thickness of the tail end of the outgoing strip O, which in the present machine is a small fraction of an inch, the stroke of the pressure fluid cylinders 258 and 259 may be relatively short and the resulting angle of inclination of the raised platform 248 need only be a few degrees.

An entry carriage 271 is supported for reciprocation toward and away from the O-frame 28 by guide means 272 carried by the platform 248. The entry carriage 271 is reciprocated by means 273. With certain exceptions noted hereinbelow, the detailed description of the exit carriage 156, guide .means 157 and reciprocation means 158 given hereinabove Will apply also to the entry carriage 271, guide means 272 and reciprocation means 273 as well as to parts thereof having corresponding parts described above. Thus, parts of the entry carriage 271, guide means 272 and reciprocation means 273 correspond to parts of the above-described exit carriage 156, guide means 157 and reciprocation means 158 will be referred to by the same reference numerals thereas with the suffix A added thereto.

It will be noted that the pressure lluid cylinders 179 and 179A of the reciprocation means 158 and 273 are both on the same side of the machine 10, that being the right side as viewed in FIG. 1. Further, the cylinder 179A (FIGS. 9 and l0) has a longer stroke than does the cylinder 179 and the contact 196A and 197A of the wedges 198A, 199A, 201A and 202A are longer than the corresponding contact faces of the corresponding wedges in the reciprocating means 158. Also, the contact surfaces 196A and 197A are sloped in the opposite direction, with respect to the path travelled by the strips O and I, as the surfaces 196 and 197. As a result, retraction of the piston rod 182A of the cylinder 179A results, as in the case of the cylinder 179, in inward movement of the carriage 271 toward the welding Zone.

(f) Overlap adjustment mechanism The platform 248 extends as seen at 276 (FIGS. 9-13) substantially beyond the end of the carriage 271 on the end thereof opposite the cylinder 179A, that is, the leftward end in FIGS. 9 and l0. The platform extension 276 is relatively narrow and extends along and on both sides of the cross slide 171A. The leftward and FIGS. 9 and 10) of the cross slide 171A and the extension 276 are equipped with coacting parts of an adjustable stop mechanism generally indicated at 277.

The stop and overlap adjustment mechanism 2.77 allows the inward and outward limits of entry clamp movement to be changed by adjusting the limits of reciprocation of the cross slide 171A. As a result, the spacing of the ends of the liners 223A and 224A from the trimmed end of the strip I, as Well as the amount of overlap between the incoming and outgoing sheets as seen in FIG. 14, can be changed. Thinner strips, being normally less stiff than thicker strips, resist deflection over a lesser unsupported extent, as between the entry noses and the welding rollers, than would thicker strips. Also, the optimum overlap for 13 a pair of thin strips may be substantially less than the optimum overlap for relatively thick strips.

Turning to the stop mechanism 277 (FIGS. 9, l0, 11, and 13), the same includes a pair of spaced abutements 278 and 279 afiixed to the upper surface of the cross slide 271A. In the particular embodiment shown, the abutments 278 and 279 are faced with suitable shims 281 and 282 removably aflixed thereto by any convenient means such as screws, not shown. A T-shaped member 283 is fixed atop the extension 275. The T-:shaped member 283 has a leg'284 which extends across and above the slideway 172A in which the cross slide 271A is reciprocably disposed. The T-shaped member 283 alsohas an elongated head portion 286 paralleling the slideway 172A preferably on the outer or rearward side thereof. The head portion 2856 of the T-shaped member 283 rests upon the base 292 of a limit fixture 291 (FIGS. 11 and 13) recessed at 293 in the top of the extension 276. The T-shaped member 283 is atiixed to the extension 276 preferably by means of screws 287 which in the particular embodiment shown pass through holes 288 in the T-shaped member which are elongated in the axial direction of the slideway 172A. Large washers 289 are dise posed between the heads of the screws 287 and the T- shaped member 283. Thus, by loosening the screws 287, the T-shaped member 283 can be shifted axially along the slideway 172A to properly adjust the position thereof. The limit fixture 291 has upstanding blocks 296 and 297 at the opposite ends thereof, the opposed faces of which threadedly receive adjustment screws 298 and 299 which extend therefrom toward each other and are preferably coaxial. The heads of the screws 298 and 299 engage the adjacent ends of the head portion 286, adjustment of the screws 298 and 299 providing a highly precise adjustment of the head portion 286 axially of the extension 276.

An upstanding generally rectangular framework 301 rests atop the leg 284 and is preferably centered above the slideway 172A. The framework 301 has upstanding walls 300 spanning the slideway 172A and an overhanging top 302 which extends axially of the slideway 172A. Upstanding pressure fluid cylinders 303 and 304 are fixed upon the top 302 adjacent the ends thereof and have depending piston rods 306 and 307 which extend downwardly through suitable openings in the top 302 adjacent the side walls 300 of the framework 301. Generally rectangular abutment shoes 308 and 309 are rigidly aiiixed to the lower ends of the piston rods 306 and 307, respectively. The surfaces of the abutment shoes facing away from the framework 301 are relieved adjacent the lower ends thereof to form abutment portions 311 and 312. Thus, when the piston rods 306 and 307 are extended, the corresponding abutment portions 311 and 312 are inserted between the leg 284 and the opposed shims 281 and 282, respectively. This shifts the limits of travel of the cross slide 171A by an amount equal to the thickness of the interposed portions 311 and 312, and by a proportionate amount, determined by the angle of the angle blocks 186A and 187A, shifts the limits of reciprocation of the entry clamp 101. Normally the shoes 308 and 309 are lowered alternatively to effect a finite shift in the orbit of the entry clamp and thereby a finite shift in the unsupported length of the head end extending from the entry noses to the welding roll path. Thus, simply -by re'- versing the positions of the shoes 303 and 309, the inner end of the entry nose travel may be set near the welding roll path for thin strips or further from the welding roll path for thick strips without changing the length of the nose travel. The screws 298 and 299 may be used to effect a line adjustment of the entry clamp orbit, again Without changing the length thereof, to complement the gross adjustment of orbit position effected as-above described by alternative lowering of the shoes 308 and 309.

On the other hand, exchanging the shim 282 for another of different thickness will alter the trimmed length of strip end extending from the entry noses and, hence,

308 and 309, will alter the amount of overlap between the head and tail strip ends.

OPERATION (a) Pre-weld operation The machine 10 was developed to quickly and reliably overlap weld the end of succeeding relatively thin strips of steel, the resulting strip being uniform with narrow limits throughout its length and hence through the welded joints.

Turning now to a preferred mode of operation of the machine 10 (FIGS. 1, 2 and 3), with the clamps 101 and 102 open, the upper weld and planishing rolls raised and the rest of the machine 10 generally positioned as shown in the drawings, the tail end of an outgoing strip O is drawn forwardly through the opening 33 of the O-frame 28 by any convenient means, not shown. The tail end of the outgoing strip O continues to move forwardly through the machine 10 until it nears the exit side of the open shear 46 at which point it is stopped by any convenient means, not shown, preferably controlled from the operators instrument panel mounted on the machine 10. When the tail end stops, the exit clamp 102 is closed by retracting the piston rods of the exit clamp cylinders 226 and 227. With the outgoing strip O thus snugly disposed between the core 209 (FIG. 4) and the bedplate 206, energization of the electromagnet 207 attracts same to the bedplate 206 thus clamping the tail tightly therebetween. The liners 223 and 224 of the clamp noses 216 and 217 are spaced slightly from the strip O being clamped to limit displacement thereof vertically and, hence, to prevent buckling thereof during shearing or welding.

With the clamping of the tail completed, the shear 46 is energized. Thus, the cylinders 54 (FIG. 1) and 59 move the upper and lower blades 47 and 48 together to trim the excess length from the tail of the outgoing strip O. The shear is then opened.

If the waste from the strip tail is longer than the distance between the shear planes of the shear 46, the usual Waste piece will be deposited between the edges of the lower blade 48 and an additional waste will fall on the entry side of the shear 46, such waste being subsequently removed by the operator.

The head end of an incoming strip I (FIG. 3) preferably fed from a suitable roll R (FIGS. 3 and 15) by any convenient means such as conventional drive rollers D is jogged across the top of the entry carriage 271, through the open entry clamp 101 and shear 46 and past the trimmed end of the outgoing strip O. Prior to or during the afore-mentioned movement of the strip head toward the trimmed tail, the carriage 271 is caused to rise somewhat so as to allow the head to overlap the tail of the outgoing strip without interfering therewith. This over-l lapping is accomplished by energization of the lift pressure fluid cylinders 258 and 259 (FIG. 9) the resulting extension of which raises the inner portion of the platform 248 and pivots said platform about the axes of the pivot bearings 246 and 247. The upward pivoting motion of the platform 248 results in the required rise of the head carried thereby. After the head has overlapped the tail by the desired amount, the pressure fluid cylinders 258 and 259 are de-energized thereby allowing the piston rods 263 and 264 thereof to fall. As a result, the platform 248 pivots downwardly to its normal lowermost position shown in FIG. 8 and allows the head to rest on the trimmed tail. Suitable means, preferably the exit equipment 99, (FIG. 4) detects the position of the drive side edge of the clamped and trimmed outgoing strip and as disclosed in the above-mentioned application Ser. No. 553,970 causes the entry equipment 98 to position the head of an incoming strip I transversely, whereby the incoming strip I is precisely axially aligned with outgoing strip O.

The entry clamp pressure iiuid cylinders 226A and 15 227A (FIG. 8) are then energized to lower the core 208A against the head end lying on the bedplate 206A. The electromagnet vwindings are thereafter energized and the clamp 101 thus firmly grips the incoming strip I.

Thereafter, the entry clamp 101 with the head of the incoming strip I is retracted rearwardly away from the welding zone which results in a certain amount of slack in the incoming strip I as generally indicated at S in FIGS. 3 and 15. More particularly, the entry cross slide cylinder 179A is energized to extend its piston rod and thus to move the cross slide 171A leftwardly as seen in FIGS. 9 and 10. The leftwardly moving angle blocks 186A and 187A, carried by the cross slide 171A, slide along the contact surfaces 197A of the wedge members 199A and 202A and move same away from the welding zone to thereby move the carriage away from the 4welding zone. The head, held by the clamp 101, is therefore also moved away from the welding zone. Upon such retraction of the entry clamp and head, the shear 46 is once again closed, the blades 47 and 48 thereof trimming the head end of the strip I.

After the shear 46 opens, the entry cross slide cylinder 179A is reversed to move the carriage 271, entry clamp 101 and the head back toward the welding zone. Again, the carriage 271 is caused to rise as the head moves forwardly to allow same to overlap the tail. When the head reaches its forward limit of motion determined by the stop mechanism 277, the carriage 271 drops.

(b) Strip overhang adjustment It will be noted that as the entry clamp 101 is dropped to its lowermost position as above described, the head end of the incoming strip I is curved upwardly at an angle R1 (FIG. 14) as it strikes the upper surface of the tail. Correspondingly, the tail would normally be curved downwardly by substantially the same amount. The clamp nose liners 223, 224 and 223A, 224A prevent significant deflection of the portions of the strips therebetween, most of the deflection of the strips thus being between the ends of the entry and exit clamp liner pairs.

If the entry and exit clamps are too close, the angle R1 tends to become excessively large, particularly for thicker strips, and the elastic limit of the head and tail is exceeded. In such case, the head and/or tail will fold sharply so that one or more creases will appear in the concave sides thereof. Suc'h creases are not removed in the lwelding and planishing processes and thus render the finished strip defective.

On the other hand, if the entry and exit clamps are spaced too far apart, the unsupported portions of the strips therebetween, particularly in thinner strips, will tend to buckle during welding. As a result, it is desirable that the entry and exit clamps be placed relatively close together for thin strips to provide adequate support and less close together for thicker strips so as to avoid creasmg.

rI'hus, for the relatively thin strips indicated at I2 and 02, the clamp noses preferably are disposed close together as indicated in dotted lines in FIG. 14, which positions correspond to the location of the entry and exit clamps 101 and 102 in the remaining figures. However, whenv relatively thick strips, such as those indicated in the solid lines in FIG. 14 at I1 and O1 are being overlapped, entry and exit clamps 101 and 102 are preferably located somewhat farther from the welding zone and from each other, than is shown in FIGS. 3-10. Such adjustment of clamp position for welding would normally be carried out by the operator prior to the steps of operation above described. j

Retraction of the eXit clamp from the welding zone is readily carried out by energization of the cylinder 179 (FIG. 7) to extend its piston rod 182 and therewith the cross slide 171 rightwardly. Rightward movement of the cross slide 171 slides the angle blocks 1816 and 187 fixed thereto along the contact surfaces 196 and 197 of the wedge blocks 198, 199, and 201, 202 fixed to the exit 16 carriage 156 to move said carriage, and therewith the exit clamp 102, away from the welding zone.

It will be noted that the travel of the exit carriage 156 is substantially shorter than the travel of the entry car riage 271. In fact, the travel of the exit carriage 156 is preferably equal to the rearward shift of the orbit of the entry clamp 101 (FIGS. 8 and 9) resulting from a reversal of the positions of the shoes 308 and 309 of the stop mechanism 277. p

When the exit clamp is retracted from the welding zone for properly gripping a thick strip, the orbit of the entry clamp 101 is preferably also shifted away from the welding zone, thereby shifting the inner end of such orbit away from the welding zone. The shoes 308 and 309 of stop mechanism 277 as shown in FIGS. 9 and l0 are arranged to place the entry clamp orbit in its position nearest the welding zone. To shift the entry clamp orbit out-l wardly a step, the cylinder 303 is energized to drop the shoe 308 and the cylinder 304 is energized to raise the shoe 309. Appropriate concurrent jogging of the cross slide 171A by cylinder 179A moves the abutment 278 leftwardly away from the leg portion 284 to allow the shoe 308 to freely drop between such leg and the shim 281. Subsequently, the cross slide 171A may be returned rightwardly to its new limiting position determined by the shoe 308. Thus, when the shoes 308 and 309 move to new positions opposite those shown in the drawings, the orbit of the cross slide 1.71 is shifted rightwardly (FIG. 9 and l0) by the thickness of the lower portion 311 and 312, and the orbit of the entry clamp is shifted rearwardly as intended.

As mentioned above, adjustment of the entry clamp orbit position is not limited to the two spaced locations provided by reversing the shoes 308 and 309. A continuous fine adjustment of the entry clamp orbit position between and beyond these two locations may be had by loosening the screws 187 of the stop mechanism 277 and shifting the T-member 283 forwardly or rearwardly by adjusting the screws 298 and 299. Normally, however, once an initial adjustment of screws 298 and 299 has been made, the gross two-position adjustment allowed by reversal of shoes 308 and 309 will suflce to cover the normal range of strip thicknesses handled by the machine 10.

Referring again to FIG. 14, the optimum amount of overlap of the head and tail normally is directly related to the thickness thereof. Too much overlap relative to strip thickness is undesirable since it produces a weld seam of large cross-sectional area lwhich cannot readily be planished to a thickness substantially equal to the rest of the strips. Too little overlap relative to strip thickness, on the other hand, may allow the head to slip off the tail during welding producing a defective seam or none at all. Thus, it is desirable that the machine 10 'be adjusted, prior to feeding of the strips thereto, to provide the proper overlap for the strip thickness to be handled. Assuming the apparatus 277 (FIG. l2) as shown to be adjusted for proper thin strip overlap, same can be adapted to thick strips, i.e., greater overlap, by replacement of the shim 281 by a thinner one or by complete removal thereof. Such moves the leftward limit of the cross slide 171A farther leftwardly and, hence, moves the forward limit of the entry clamp nearer the tail so as to increase headtail overlap. Since the shim 282 has not been changed, the rearward limit of the clamp travel is unchanged and therewith the overhang of head from entry clamp.

Alternatively overhang can be increased by leaving the shim 281 alone and shortening the shim 282 in effect by omission or replacement. This leaves the clamp-weld roller distance unchanged at welding but lengthens the clamp shear distance at trimming thus producing a longer headclamp overhang and thereby a greater head-tail overlap. Whether it is the shim 281 or the shim 282 that is adjusted, it is an elongation of the entry clamp orbit which effects an increase in head-tail overlap. Conversely, reduction of head-tail overlap may .be effected by reduction of entry clamp orbit length, as by increasing the length of the shims 281 and 282. Normally the magnitude of the elongation or contraction of the orbit will be a small fraction of the shift of orbit desired for a typical shift from thick stock to thin stock or vice versa. Also a rather close relationship of head-tail overlap to thickness may be required where provision of one head-clamp overhang setting for thick strips of quite widely varying thickness and just one other overhang setting for any thinner strips may be satisfactory.

(c) Welding and planishing Once the sheared head and tail ends are overlapped, the O-frame 28 is energized through the screw 41 and motor 42 to move toward the operator, that is, to the right seen in FIG. l, in order to move the shear 46 past the strips I and O and move the welding rollers 71 and 72 theretoward. During such movement, the weld cylinder 74 is energized to move the normally raised upper welding electrode 71 downwardly toward the lower roller 72 and maintain a predetermined pressure on the seam formed by the overlapped head and tail located therebetween. The weld current source 81 is energized by this time and through -bus bars 78 and 79 energizes the welding electrodes 71 and 72. The welding electrodes roll along and weld together the overlapped strip ends as the O-frame 28 continues to move rightwardly. After completion of welding, the source 81 is de-energized and the cylinder 74 reversed to raise the upper electrode 71.

The direction of motion in the O-frame 28 is then reversed and the planishing cylinders 91 and 92 are energized to urge the planishing wheel 86V downwardly into contact with the weld seam at its rightward (FIG. l) end. The planishing rollers S6 and 87 exert suiiicient force upon the freshly welded sea-m to flatten same substantially to the thickness of the rest of the strips I and O. As the O-frame 28 moves the planishing wheels off the leftward (FIG. l) end of the weld seam, cylinders 91 and 92 raise the upper planishing wheel 86. The leftward motion of the O-frame continues until it has returned to its rest position shown in solid lines in FIG. 1. The clamps 101 and 102 (FIG. 3) then open yand the welded strip is free to move forwardly therethrough in response to any convenient motive power source, not shown. Thus, the machine is left in a rest condition to repeat the cycle above described when the tail of the strip I `moving therethrough appears.

(d) Compensation for overlap runout in wide strip welds Where the strips to be welded are relatively wide, i.e., a few feet or more in width, and particularly in cases where the overlap provided between the head and tail is relatively small, i.e., approximately the same as the thickness of the strips being joined, it has been found that as the welding rollers progress along the seam of overlap in front thereof gradually lessens. For example, wide strip ends initially uniformly overlapped by .050 inch prior to welding have been found to retain that overlap at the first welded end of the seam bust lose as much as .020 inch overlap, i.e., 20% at the last welded end of such weld seam. Such large percentage overlap runout has heretofore not been a problem since prior machines handling relatively narrow strips which did not exhibit such runout in overlap during Welding.

It is to correct for this runout in wide strips that the exit platform 116 (FIGS. 5 and 6) is mounted for pivotal motion upon the exit table 111. Thus, when relatively wide strips are to be welded, the pivot cylinder 134 is energized after the tail is firmly clamped. The cylinder 134 moves the lever 142 outwardly away from the welding zone to cock the tail by a small amount. The displacement of the lever 142. is chosen to provide an outward displacement of the leftward (FIGS. 6 and 7) edge of the tail by a distance equal to the anticipated runout in the weld seam. Thereafter, the tail is trimmed as above described, but due to the counterclockwise pivotal displacement of the platform 111 about the pivot screw 125, at a slight angle T. Thereafter, cylinder 134 is energized to return the tail to its original uncooked position. As a result, the trimmed tail extends somewhat farther toward the weld zone on its leftward side than on its rightward side as shown in FIG. 6. When the head and tail are overlapped, there will be the normal desired amount of overlap on the side rst to be welded and substantially more overlap on the last side of the strips to be welded, the extra overlap being equal to the contemplated runout. In consequence, as the overlap runs out ahead of the advancing welding rolls, a uniformly overlapped seam is produced. It should be noted that joined as above described, the head and tail are longitudinally aligned after Welding.

An alternate, though somewhat less desirable method of compensating for overlap runout, also makes use of the pivot cylinder 134. In this alternate method, however, the tail is clamped and trimmed prior to cocking thereof and is cocked, by extension of the cylinder 134, immediate prior to welding. As a result, the edge of the tail last to be welded will be overlapped by the head by an amount in excess of the desired welded overlap. Runout of the excess overlap during welding results in a rfinished seam of constant overlap throughout its length. However, this alternate method produces a composite strip in which the welded head and tail are not longitudinally aligned but are skewed slightly with respect to each other.

Although a particular preferred embodiment of the invention has been disclosed above for illustrative purposes, it will be understood that variations or modifications thereof which lie within the scope of the appended claims are fully contemplated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for welding together the head and the tail of a pair of oppositely extending elongated strips, comprising the steps:

clamping the tail of one strip in a first clamp;

moving trimming means through a location near said first clamp to trim the excess length from the tail; placing the head of the other strip in a position overlapping said tail by a first lengthwise extent;

closing a further clamp on said head;

moving said further clamp and thereby said head lengthwise away from said tail and said first clamp to create slack in the portion of said other strip adjacent lsaid head;

moving trimming means through a location between said clamps to trim the end of said head;

moving said further clamp and thereby said head lengthwise toward said first clamp to overlap the head and the tail by a second lengthwise extent not greater than said rst lengthwise extent and thereby taking up at least part of said slack in said other strip; i welding the overlapped portions of the head and the tail together; and releasing said clamps to free the welded-together strips.

2. A machine for welding together the ends of successive elongated strip-s movable longitudinally therethrough, comprising the combination:

trimming means for trimming the adjacent ends of a successive pair of strips extending in opposite directions therefrom and welding means for welding said pair of strips together, said trimming means defining a pair of shear planes spaced along the path of said strips and said welding means defining a welding zone substantially centered on one of said shear planes;

first clamp means adjacent said welding means on the opposite side of said one shear plane from the other shear plane, said first clamp means being energizable for gripping the adjacent one of said strips;

means supporting said first clamp means for limited reciprocation along the path of said strips, the distance of said first clamp means from said oneshear plane determining the amount by which the trimmed strip end of said one strip overhangs said first clamp. means; v second clamp means on the opposite side of said other plane, said second clamp means being energizable for gripping the other of said strips;

means supporting said second clamp `means for back and forth movement through an orbital path extending along said strip path;

adjustment means on said supporting means actuable for shifting the innermost and outermost positions of said second clamp means during its orbital movement along said strip path toward and away from the other of said shear planes, the range through which said adjustment means can move said innermost and outermost positions of said second clamp means along said second strip being substantially similar to the distance through which said first clamp means can move along said rst strip, shifting of said innermost and outermost positions of said second clamp means varying the amount by which the trimmed end of said other strip overhangs said second clamp means.

3. The device defined in claim 2, including further adjustment means on said means supporting said second clamp means actuable for changing the leng-th of said orbital path, such change in the orbital path length varying the overlap of said strips when said second clamp means is at the innermost end of its orbital path of movement.

4. The device defined in claim 2 including a platform carrying said supporting means for one of said clamp means, a fixed base, means for slidably supporting said platform upon said base for movement in a plane substantially parallel to the path of said strips, means pivotally securing said platform to said base and means energizing for pivoting said platform about said pivot means to cock the strip held by said one of said clamp means.

5. The device defined in claim 2 including means for pivotally mounting said means supporting one of said clamps for rotation about an axis parallel to the plane of said strips and transverseto the longitudinal axis of said strips; and

means energizable for pivoting said means supporting said one of said clamps about said axis in a manner to raise the corresponding one of said clamp means and thereby the free end of the corresponding one of said strips for overlapping the remaining strip.

6. A method for compensating for weld seam runout in overlap welding of the ends of a pair of oppositely extending, relatively wide strips overlapped by an amount corresponding generally in magnitude to the thickness thereof, comprising the steps:

clamping one of said strips in a position precisely axially aligned with the other of said strips; cocking the end to be overlapped of said one strip by pivoting` same about an axis perpendicular` thereto said axis being closely spaced from one side edge of said one strip and to a preselected plane perpendic- 60 2O f that-the longitudinal axis thereof is moved out of per.- pendicular relationship with said plane;

trimming said one strip along the intersection of said plane and said one strip; pivotally returning said one strip to its aligned condition with respect -to the other strip after trimming` thereof, so that the trimmed edge of said one strip is angled wtih respect to the other strip;

squarely trimming the adjacent end of the other strip and placing same in an overlapped condition with the one strip so that the overlap of said strips at the side edge thereof nearest said pivot axis'corresponds to the amount of overlap desired uniformly along the seam therebetween, running welding electrodes along the overlapped portion of the strips above and below said overlapped portion in a direction extending from the side of strips adjacent said pivot axis;

whereby the tendency toward overlap runout during welding as said rollers advance toward the other side of said strips will be compensated for by the extra overlap provided at the other side of said strips.

7. A machine for welding together the ends of rst and second strips movable longitudinally therethrough along a strip path, comprising the combination:

trimming means for trimming the adjacent ends of said first and second strips extending in opposite directions therefrom and welding means positioned in close proximity to said trimming means for welding said ends together;

first clamp means on one side of said trimming means and welding means and energiza-ble for gripping the adjacent rst strip;

second clamp means on the other side of said trimming means and welding means energizable for gripping the second strip;

means supporting said second clamp means for movement through an orbital path including back-andforth movement along said strip path and fo-r up-anddown movement relative to said strip path;

whereby said orbital path of said second clamp means will, during one movement, position one of said strips above the other strip to thereby prevent a jamming of the leading end of said first strip with the trailing end of said second strip, said movement of said second clamp means, during a second movement, moving said second strip into engagement with said first strip to thereby overlap said strips for welding.

References Cited UNITED STATES PATENTS 2,911,515 11/1959 Cooper 219-79 2,957,071 10/1960 Cooper et al. 219-82 3,017,495 1/1962 Woodward 219--82 3,068,347 12/1962 Tribe 219-82 3,102,189 8/1963 Jones et al. 219-82 3,256,419 `6/1966 Taylor et al. 219-83 I 3,298,587 l/l967 Seelofrr et al 228-5 JOSEPH V. TRUI-IE, Primary Examiner P. Wl GOWDEY, Assistant Examiner 

